Captioning is defined as the rendering of speech and other audible information (112) into written language (111) or transcription of the audio. Audio captions (111) may be written transcriptions or written translations of the audio portion (112) of television programs (113) and other video materials, such as training tapes, corporate communications, etc.
Closed captioning was developed in the 1970's to allow deaf and hard of hearing viewers to understand television programming. Since that time, many other uses of captioning have been discovered, including its use to teach foreign languages. Individuals can use captioning to comprehend audio or video media. Individuals with normal hearing may also use captioning to comprehend a television program in public areas with high noise levels, or to comprehend a television program recorded on a different language.
Anything that is produced on video or broadcast can be captioned. A content provider (i.e. television network) may use online captioning or offline captioning to generate a captioning text stream. Offline captioning is performed “after the fact” in a studio. Examples of offline captioning include television game shows, videotapes of movies, and corporate videotapes (e.g., training videos). The text of the captions is created on a computer, and the captions stream (701) is synchronized to the video (702) using time codes. The captions are then transferred to the videotape before it is broadcast or distributed. On broadcast television closed captions are encoded, or imbedded, into Line 21 of the broadcast signal, so that they are visible only when decoded by caption-capable television sets.
A limitation of today's captioning systems is that, since captions are encoded and transmitted on the media stream (e.g., on Line 21 of a broadcast video stream), and are decoded and displayed by the media player or broadcast receiver (e.g., a TV set), there is not way to provide on demand, selectable, personalized, captioning services that could be individually requested by people attending a program played on a media player or broadcast receiver (e.g., a TV set on a public place, like a cafeteria or a bus station).
In fact, not every people attending the same program have a need, or the same need, of receiving captioning services. For example, text captions of a TV program played on a public place (e.g., a cafeteria) may be a need for a deaf person, but not for the other people attending the TV program. Textual captions displayed on a TV set, may be needed by a particular person, but may disturb the visual comfort of other people attending the same program on the same TV set. Also, when a TV program is being received on a public place (e.g., on a TV set on a pub in London), displaying textual captions on a selected language (e.g., French) may be needed by a foreigner (e.g., by a French national), but not by most people (e.g., Britons) attending the program on the pub. Thus, displaying captions on a TV set may be needed by some people, but may disturb other.
The popularity of wireless portable computers such as handheld devices (100) or cell phones for connecting to the Internet (108) is increasing as users interest becomes pervasive and as users are more often working in mobile environments. At the same time, the popularity of making network connections using connection services that charge fees based upon the duration of connections (such as cellular services, which are commonly used for wireless connections from portable computers) is also growing. When using this type of relatively expensive connection, the longer the user is connected, the higher the connection charges will be. This prevents, by instance, a user to remain wirelessly connected to a simulcast web service to receive on-line captions while attending a broadcast movie. Wireless connections also tend to have high network latencies, due to the limited bandwidth available and the extra network hops (e.g. gateways) that are involved with intermediate wired and wireless nodes. As a result, a user may suffer long delays preventing webcast captions to be received and played on synchronism with a (simulcast) broadcast program. Finally, a major drawback is that long wireless connections drains lots of battery charge.
Therefore, there is a need to provide on demand personalized, captioning services to people receiving broadcast programs on mobile environments.